SEC Filings

Contractual maturities of gross lease receivables as of December 31, 2017, are as follows (in millions):

Fiscal Year

Amount

2018

$

44.4

2019

37.0

2020

26.6

2021

13.1

2022

6.4

2023 and thereafter

0.5

Total

$

128.0

Operating Leases. The Company's operating lease terms are generally less than five years. Future minimum lease payments related to non-cancellable portion of operating leases as of December 31, 2017, are as follows (in millions):

Fiscal Year

Amount

2018

$

42.6

2019

41.2

2020

34.0

2021

19.5

2022

8.4

2023 and thereafter

0.7

Total

$

146.4

Contingent rental revenue relating to operating lease arrangements were not material for the periods presented.

NOTE 6. INTANGIBLE ASSETS

The following table summarizes the components of gross intangible asset, accumulated amortization, and net intangible asset balances as of December 31, 2017, and 2016 (in millions):

December 31, 2017

December 31, 2016

Gross Carrying Amount

Accumulated Amortization

Net Carrying Amount

Gross Carrying Amount

Accumulated Amortization

Net Carrying Amount

Patents and developed technology

$

156.0

$

(140.2

)

$

15.8

$

158.7

$

(141.6

)

$

17.1

Distribution rights and others

9.2

(9.2

)

—

9.2

(9.1

)

0.1

Customer relationships

28.6

(18.4

)

10.2

28.6

(14.3

)

14.3

Total intangible assets

$

193.8

$

(167.8

)

$

26.0

$

196.5

$

(165.0

)

$

31.5

Amortization expense related to intangible assets was $12.9 million, $18.2 million, and $24.4 million for the years ended December 31, 2017, 2016, and 2015, respectively.

The estimated future amortization expense related to intangible assets as of December 31, 2017, is as follows (in millions):